This invention relates to an automatic performance device such as a sequencer, an automatic accompaniment device, an automatic rhythm performance device or the like device used in an electronic musical instrument and, more particularly, to an automatic performance device having a function of changing a tempo during an automatic performance.
In the prior art, there is known an automatic performance device of a type which stores performance information supplied from a keyboard of an electronic musical instrument or a computer and reproduces a tone played on the basis of the stored performance information. In this type of automatic performance device, performance information is read from a memory in accordance with a tempo clock and a tone signal is generated on the basis of this performance information. In this case, the frequency of the tempo clock can be freely variably controlled by operating a tempo setting switch or the like and, therefore, the operator or player can freely change the tempo of playback performance to a desired tempo by operating such tempo setting switch or the like.
The tempo of performance can be changed continuously by operation of the tempo setting switch or discontinuously by operation of a suitable up-down switch or the like switch. There has also recently appeared a device according to which the tempo of performance can be decelerated or accelerated gradually at a certain rate by operation of switches such as a ritardando switch and an accelerando switch corresponding to tempo words such as ritardando and accelerando.
In the prior art automatic performance devices, the performance tempo is changed continuously or discontinuously by changing the performance tempo during performance by means of a tempo setting operator in the form of a knob or a switch and the tempo of a music piece performed thereby is variably changed and variety is imparted to the music piece performed.
In the prior art automatic performance device, however, in a case where the operator desires to restore the performance tempo to a previous tempo employed before the start of a ritardando or accelerando processing immediately upon completion of such processing (so-called "a tempo"), the operator himself must remember the value of the previous tempo before the start of such processing and, immediately upon completion of such processing, must operate the tempo setting operator to restore the current tempo value to the previous tempo value. Further, in a case where, after having changed the performance tempo during a performance, the operator desires to restore the current performance tempo to the tempo used at the start of the performance (so-called "tempo primo"), the operator must likewise remember the initial tempo value at the start of the performance and operate the tempo setting operator at a time point when he desires to restore the tempo to change the current tempo value to the initial tempo value.
In the prior art automatic performance devices, there is known a device in which a ritardando processing is synchronized with an accelerando processing and the ritardando processing is treated as being effective only during a fill-in performance so that the performance tempo is gradually decelerated only during the fill-in performance and the performance tempo is restored to a tempo employed before the ritardando processing simultaneously with completion of the fill-in performance (a tempo). In this device, however, when the ritardando processing is performed independently without synchronizing with the fill-in performance, no operation for restoring the performance tempo to a tempo before starting of the ritardando processing (a tempo) is automatically performed and, therefore, the operator must operate, in the same manner as described above, the tempo setting operator to change the current tempo to the tempo value employed before the ritardando processing immediately upon completion of the processing.